Livaan, Cultist of Tiamat

Whenever you cast a noncreature spell, target creature gets +X/+0 until end of turn, where X is that spell's mana value.
Choose a Background (You can have a Background as a second commander.)

Gilded Lotus

Wheel of Fate

Suspend 4—{1}{R} (Rather than cast this card from your hand, pay {1}{R} and exile it with four time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
Each player discards their hand, then draws seven cards.

Sakura-Tribe Elder

Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Everflowing Chalice

Multikicker {2} (You may pay an additional {2} any number of times as you cast this spell.)
Everflowing Chalice enters with a charge counter on it for each time it was kicked.
{T}: Add {C} for each charge counter on Everflowing Chalice.

Minsc & Boo, Timeless Heroes

When Minsc & Boo, Timeless Heroes enters and at the beginning of your upkeep, you may create Boo, a legendary 1/1 red Hamster creature token with trample and haste.
+1: Put three +1/+1 counters on up to one target creature with trample or haste.
−2: Sacrifice a creature. When you do, Minsc & Boo, Timeless Heroes deals X damage to any target, where X is that creature's power. If the sacrificed creature was a Hamster, draw X cards.
Minsc & Boo, Timeless Heroes can be your commander.

Basalt Monolith

Basalt Monolith doesn't untap during your untap step.
{T}: Add {C}{C}{C}.
{3}: Untap Basalt Monolith.

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Elvish Visionary

When Elvish Visionary enters, draw a card.

Ranger's Guile

Target creature you control gets +1/+1 and gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Ring of Kalonia

Equipped creature has trample. (It can deal excess combat damage to the player or planeswalker it's attacking.)
At the beginning of your upkeep, put a +1/+1 counter on equipped creature if it's green.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Arbor Colossus

Reach
{3}{G}{G}{G}: Monstrosity 3. (If this creature isn't monstrous, put three +1/+1 counters on it and it becomes monstrous.)
When Arbor Colossus becomes monstrous, destroy target creature with flying an opponent controls.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Mutant's Prey

Target creature you control with a +1/+1 counter on it fights target creature an opponent controls. (Each deals damage equal to its power to the other.)

Terrifying Presence

Prevent all combat damage that would be dealt by creatures other than target creature this turn.

Mercadian Bazaar

Mercadian Bazaar enters tapped.
{T}: Put a storage counter on Mercadian Bazaar.
{T}, Remove any number of storage counters from Mercadian Bazaar: Add {R} for each storage counter removed this way.

Mountain

Hoarding Dragon

Flying
When Hoarding Dragon enters, you may search your library for an artifact card, exile it, then shuffle.
When Hoarding Dragon dies, you may put the exiled card into its owner's hand.

Lu Bu, Master-at-Arms

Haste; horsemanship (This creature can't be blocked except by creatures with horsemanship.)

Gruul Ragebeast

Whenever Gruul Ragebeast or another creature you control enters, that creature fights target creature an opponent controls.

Bristling Backwoods

Bristling Backwoods enters tapped.
When Bristling Backwoods enters, it deals 1 damage to target opponent.
{T}: Add {R} or {G}.

Forest

Plant Beans

You may play an additional land this turn. (Then exile this card. You may cast the creature later from exile.)

Beanstalk Wurm

Beanstalk Wurm // Plant Beans

Dragon Mantle

Enchant creature
When Dragon Mantle enters, draw a card.
Enchanted creature has "{R}: This creature gets +1/+0 until end of turn."

Flametongue Kavu

When Flametongue Kavu enters, it deals 4 damage to target creature.

Gruul Keyrune

{T}: Add {R} or {G}.
{R}{G}: Gruul Keyrune becomes a 3/2 red and green Beast artifact creature with trample until end of turn.

Hammer of Purphoros

Creatures you control have haste.
{2}{R}, {T}, Sacrifice a land: Create a 3/3 colorless Golem enchantment artifact creature token.

Curse of Chaos

Enchant player
Whenever a player attacks enchanted player with one or more creatures, that attacking player may discard a card. If the player does, they draw a card.

Ancient Bronze Dragon

Flying
Whenever Ancient Bronze Dragon deals combat damage to a player, roll a d20. When you do, put X +1/+1 counters on each of up to two target creatures, where X is the result.

Goblin Game

Each player hides at least one item, then all players reveal them simultaneously. Each player loses life equal to the number of items they revealed. The player who revealed the fewest items then loses half their life, rounded up. If two or more players are tied for fewest, each loses half their life, rounded up.

Insurrection

Untap all creatures and gain control of them until end of turn. They gain haste until end of turn.

Sylvan Caryatid

Defender, hexproof
{T}: Add one mana of any color.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Mistcutter Hydra

This spell can't be countered.
Haste, protection from blue
Mistcutter Hydra enters with X +1/+1 counters on it.

Mana Flare

Whenever a player taps a land for mana, that player adds one mana of any type that land produced.

Gift of the Viper

Put a +1/+1 counter, a reach counter, and a deathtouch counter on target creature. Untap it.

Sol Ring

Titanic Growth

Target creature gets +4/+4 until end of turn.

Firebreathing

Enchant creature
{R}: Enchanted creature gets +1/+0 until end of turn.

Brash Taunter

Indestructible
Whenever Brash Taunter is dealt damage, it deals that much damage to target opponent.
{2}{R}, {T}: Brash Taunter fights another target creature.

Titan's Strength

Target creature gets +3/+1 until end of turn. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Zhur-Taa Druid

{T}: Add {G}.
Whenever you tap Zhur-Taa Druid for mana, it deals 1 damage to each opponent.

Charmbreaker Devils

At the beginning of your upkeep, return an instant or sorcery card at random from your graveyard to your hand.
Whenever you cast an instant or sorcery spell, Charmbreaker Devils gets +4/+0 until end of turn.

Where Ancients Tread

Whenever a creature you control with power 5 or greater enters, you may have Where Ancients Tread deal 5 damage to any target.

Fling

As an additional cost to cast this spell, sacrifice a creature.
Fling deals damage equal to the sacrificed creature's power to any target.

Game of Chaos

Flip a coin. If you win the flip, you gain 1 life and target opponent loses 1 life, and you decide whether to flip again. If you lose the flip, you lose 1 life and that opponent gains 1 life, and that player decides whether to flip again. Double the life stakes with each flip.

Druid of the Emerald Grove

When Druid of the Emerald Grove enters, search your library for up to two basic land cards and reveal them, then roll a d20.
9 or less | Put those cards into your hand, then shuffle.
10—19 | Put one of those cards onto the battlefield tapped and the other into your hand, then shuffle.
20+ | Put those cards onto the battlefield tapped, then shuffle.

Flame-Wreathed Phoenix

Flying
Tribute 2 (As this creature enters, an opponent of your choice may put two +1/+1 counters on it.)
When Flame-Wreathed Phoenix enters, if tribute wasn't paid, it gains haste and "When this creature dies, return it to its owner's hand."

Starstorm

Starstorm deals X damage to each creature.
Cycling {3} ({3}, Discard this card: Draw a card.)

Zhur-Taa Ancient

Realm-Scorcher Hellkite

Bargain (You may sacrifice an artifact, enchantment, or token as you cast this spell.)
Flying, haste
When Realm-Scorcher Hellkite enters, if it was bargained, add four mana in any combination of colors.
{1}{R}: Realm-Scorcher Hellkite deals 1 damage to any target.

Command Tower

{T}: Add one mana of any color in your commander's color identity.

Colossus of Akros

Defender, indestructible
{10}: Monstrosity 10. (If this creature isn't monstrous, put ten +1/+1 counters on it and it becomes monstrous.)
As long as Colossus of Akros is monstrous, it has trample and can attack as though it didn't have defender.

Burning-Tree Emissary

When Burning-Tree Emissary enters, add {R}{G}.

Genesis Hydra

When you cast this spell, reveal the top X cards of your library. You may put a nonland permanent card with mana value X or less from among them onto the battlefield. Then shuffle the rest into your library.
Genesis Hydra enters with X +1/+1 counters on it.

Stuffy Doll

Indestructible
As Stuffy Doll enters, choose a player.
Whenever Stuffy Doll is dealt damage, it deals that much damage to the chosen player.
{T}: Stuffy Doll deals 1 damage to itself.

Rubblebelt Raiders

Whenever Rubblebelt Raiders attacks, put a +1/+1 counter on it for each attacking creature you control.

Chandra, Pyromaster

+1: Chandra, Pyromaster deals 1 damage to target player or planeswalker and 1 damage to up to one target creature that player or that planeswalker's controller controls. That creature can't block this turn.
0: Exile the top card of your library. You may play it this turn.
−7: Exile the top ten cards of your library. Choose an instant or sorcery card exiled this way and copy it three times. You may cast the copies without paying their mana costs.

Ordeal of Nylea

Enchant creature
Whenever enchanted creature attacks, put a +1/+1 counter on it. Then if it has three or more +1/+1 counters on it, sacrifice Ordeal of Nylea.
When you sacrifice Ordeal of Nylea, search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Destructive Revelry

Destroy target artifact or enchantment. Destructive Revelry deals 2 damage to that permanent's controller.

Gruul Guildgate

Gruul Guildgate enters tapped.
{T}: Add {R} or {G}.

Blasphemous Act

This spell costs {1} less to cast for each creature on the battlefield.
Blasphemous Act deals 13 damage to each creature.

Creepy Doll

Indestructible
Whenever Creepy Doll deals combat damage to a creature, flip a coin. If you win the flip, destroy that creature.

Gruul Cluestone

{T}: Add {R} or {G}.
{R}{G}, {T}, Sacrifice Gruul Cluestone: Draw a card.

Feral Animist

{3}: Feral Animist gets +X/+0 until end of turn, where X is its power.

Archetype of Aggression

Creatures you control have trample.
Creatures your opponents control lose trample and can't have or gain trample.

Traitorous Blood

Gain control of target creature until end of turn. Untap it. It gains trample and haste until end of turn.

Heartless Hidetsugu

{T}: Heartless Hidetsugu deals damage to each player equal to half that player's life total, rounded down.

Rummaging Goblin

Court of Garenbrig

When Court of Garenbrig enters, you become the monarch.
At the beginning of your upkeep, distribute two +1/+1 counters among up to two target creatures. Then if you're the monarch, double the number of +1/+1 counters on each creature you control.

Nessian Wilds Ravager

Tribute 6 (As this creature enters, an opponent of your choice may put six +1/+1 counters on it.)
When Nessian Wilds Ravager enters, if tribute wasn't paid, you may have Nessian Wilds Ravager fight another target creature. (Each deals damage equal to its power to the other.)

Evolving Wilds

{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.

Desert of the Indomitable

Desert of the Indomitable enters tapped.
{T}: Add {G}.
Cycling {1}{G} ({1}{G}, Discard this card: Draw a card.)